Storage containers include an open top base for storage and a lid to close the base. The lid and base mate to define the closure and seal. Thermoformed, rectangular storage containers are known in the art.
In considering container design, price and value, and sometimes price alone, often drive the container design; the materials used; and the ultimate construction and performance of storage containers. There are often tradeoffs in the quality of the container design and the intended use of the container. Additionally, the increased cost of resin has made container design important to optimize the use of resin while concurrently providing a quality container, e.g. providing a lightweight container using less resin.
Many types of storage containers are available in the marketplace, including for food storage and the like. These containers generally fall under several categories, including (1) single use or disposable containers made of plastic or paper; (2) semi-durable containers which are disposable after a few uses; and (3) durable containers manufactured for multiple uses.
The present invention is directed to thermoformed, rectangular disposable thermoplastic storage containers. The amount of plastic used adds to the weight and to the cost of the container. As previously stated, rectangular thermoformed storage containers are known in the art. These containers are made by known thermoforming techniques such as vacuum thermoforming, pressure thermoforming or mechanical thermoforming, although the most prevalent thermoforming of rectangular storage containers is vacuum thermoforming with a plug assist. A problem experienced in making rectangular thermoplastic containers as opposed to, for example, square or cylindrical containers, is that rectangular containers have different strength issues in the longer front and rear walls of the container. For example, with a container as shown in FIG. 1, the longer front wall A (as well as the rear wall not shown) has a propensity to buckle in the area “X” because of the larger area of unsupported material, i.e. this portion is usually thinner due to the thermoforming process and is farthest from the support corner structures. Through physical testing and Finite Element Analysis, it has been determined that area “X” as shown in FIG. 1 is where buckling is likely to occur when a load is applied to the container. Such buckling may cause container failure and consequently customer dissatisfaction with the container. One current method to avoid buckling is the use of more plastic which increases the strength of the container front and rear walls. However, this also increases the weight of the container and the cost of the container.
Accordingly, there is a need in the market for a thermoformed, rectangular disposable thermoplastic storage container which is lightweight, attractive, easy and inexpensive to manufacture, and in which the front and rear walls are not subject to buckling.